Frame weight is really of no major importance but revolving weight is critical. Drilling out levers, brakes and seat pins just makes your bike sound like a piccolo at 25mph+! But light tubs 24 spoked wheels and drilled out chainsets makes light years of difference.
Buckley Bros. made one of the lightest racing bikes ever back in the 1930's. They used Reynolds HM tubing. The very same tubing that Titch Morris was still using right up until he closed. The Buckley Model C as a racing bike weighed only 13lbs. and this was fitted with mostly stel fittings. This is what let it down the revolving weight. The "C" was the championship model but probably more championships were won on Selbachs, Carpenters and Saxon's back then with a much heavier butted frame but with the same Chater, Constrictor/BSA kit.
Thats all for now. Keep those wheels spinning, in your memories if not still on the road. Be lucky Mick Butler Huntingdon UK.